The present disclosure relates to semiconductor device fabrication and, more particularly, to a method of reworking and stripping patterning layers using a chemical mechanical polishing process.
Pattern generation using directed self-assembly (DSA) of polymeric materials is a promising candidate to extend current lithography in sub-20 nm technologies for integrated circuit (IC) manufacture. In a typical DSA process, microphase separation of a block copolymer that is guided by an external field, either chemistry or topography, results in a well-defined pattern with sub-photolithographic resolution. Subsequently, one of the domains is selectively removed, leaving the other domain to serve as a lithographic mask for pattern transfer to underlying resist layers and eventually to the semiconductor devices. However, during the pattern transfer processes, formation of the pattern in the patterning layers may fail, leading to defects in the pattern subsequently formed in the semiconductor devices. Once failure occurs, the patterning layers need to be removed by a rework process. The rework process can include a dry etching process such as an ashing process using an oxygen plasma, or a wet cleaning process using an organic stripper solution. However, in the case of the DSA process, exposed surfaces of the patterning layers might be modified by residues of the block copolymer which makes them difficult to remove with conventional cleaning processes. Therefore, new processing methods for removing patterning layers are needed in the DSA pattern transfer process.